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tools: ynl: user space helpers

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Add "fixed" part of the user space Netlink Spec-based library.
This will get linked with the protocol implementations to form
a full API.

Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2023-06-05 12:01:06 -07:00
parent a99bfdf647
commit 86878f14d7
7 changed files with 1310 additions and 1 deletions
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79
Documentation/userspace-api/netlink/intro-specs.rst
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@ -78,3 +78,82 @@ to see other examples.
The code generation itself is performed by ``tools/net/ynl/ynl-gen-c.py``
but it takes a few arguments so calling it directly for each file
quickly becomes tedious.
YNL lib
=======
``tools/net/ynl/lib/`` contains an implementation of a C library
(based on libmnl) which integrates with code generated by
``tools/net/ynl/ynl-gen-c.py`` to create easy to use netlink wrappers.
YNL basics
----------
The YNL library consists of two parts - the generic code (functions
prefix by ``ynl_``) and per-family auto-generated code (prefixed
with the name of the family).
To create a YNL socket call ynl_sock_create() passing the family
struct (family structs are exported by the auto-generated code).
ynl_sock_destroy() closes the socket.
YNL requests
------------
Steps for issuing YNL requests are best explained on an example.
All the functions and types in this example come from the auto-generated
code (for the netdev family in this case):
.. code-block:: c
// 0. Request and response pointers
struct netdev_dev_get_req *req;
struct netdev_dev_get_rsp *d;
// 1. Allocate a request
req = netdev_dev_get_req_alloc();
// 2. Set request parameters (as needed)
netdev_dev_get_req_set_ifindex(req, ifindex);
// 3. Issues the request
d = netdev_dev_get(ys, req);
// 4. Free the request arguments
netdev_dev_get_req_free(req);
// 5. Error check (the return value from step 3)
if (!d) {
// 6. Print the YNL-generated error
fprintf(stderr, "YNL: %s\n", ys->err.msg);
return -1;
}
// ... do stuff with the response @d
// 7. Free response
netdev_dev_get_rsp_free(d);
YNL dumps
---------
Performing dumps follows similar pattern as requests.
Dumps return a list of objects terminated by a special marker,
or NULL on error. Use ``ynl_dump_foreach()`` to iterate over
the result.
YNL notifications
-----------------
YNL lib supports using the same socket for notifications and
requests. In case notifications arrive during processing of a request
they are queued internally and can be retrieved at a later time.
To subscribed to notifications use ``ynl_subscribe()``.
The notifications have to be read out from the socket,
``ynl_socket_get_fd()`` returns the underlying socket fd which can
be plugged into appropriate asynchronous IO API like ``poll``,
or ``select``.
Notifications can be retrieved using ``ynl_ntf_dequeue()`` and have
to be freed using ``ynl_ntf_free()``. Since we don't know the notification
type upfront the notifications are returned as ``struct ynl_ntf_base_type *``
and user is expected to cast them to the appropriate full type based
on the ``cmd`` member.

19
tools/net/ynl/Makefile Normal file
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@ -0,0 +1,19 @@
# SPDX-License-Identifier: GPL-2.0
SUBDIRS = lib generated samples
all: $(SUBDIRS)
$(SUBDIRS):
@if [ -f "$@/Makefile" ] ; then \
$(MAKE) -C $@ ; \
fi
clean hardclean:
@for dir in $(SUBDIRS) ; do \
if [ -f "$$dir/Makefile" ] ; then \
$(MAKE) -C $$dir $@; \
fi \
done
.PHONY: clean all $(SUBDIRS)

45
tools/net/ynl/generated/Makefile Normal file
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@ -0,0 +1,45 @@
# SPDX-License-Identifier: GPL-2.0
CC=gcc
CFLAGS=-std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow \
-I../lib/
ifeq ("$(DEBUG)","1")
CFLAGS += -g -fsanitize=address -fsanitize=leak -static-libasan
endif
TOOL:=../ynl-gen-c.py
GENS:=
SRCS=$(patsubst %,%-user.c,${GENS})
HDRS=$(patsubst %,%-user.h,${GENS})
OBJS=$(patsubst %,%-user.o,${GENS})
all: protos.a $(HDRS) $(SRCS) $(KHDRS) $(KSRCS) $(UAPI) regen
protos.a: $(OBJS)
@echo -e "\tAR $@"
@ar rcs $@ $(OBJS)
%-user.h: ../../../../Documentation/netlink/specs/%.yaml $(TOOL)
@echo -e "\tGEN $@"
@$(TOOL) --mode user --header --spec $< > $@
%-user.c: ../../../../Documentation/netlink/specs/%.yaml $(TOOL)
@echo -e "\tGEN $@"
@$(TOOL) --mode user --source --spec $< > $@
%-user.o: %-user.c %-user.h
@echo -e "\tCC $@"
@$(COMPILE.c) -c -o $@ $<
clean:
rm -f *.o
hardclean: clean
rm -f *.c *.h *.a
regen:
@../ynl-regen.sh
.PHONY: all clean hardclean regen
.DEFAULT_GOAL: all

28
tools/net/ynl/lib/Makefile Normal file
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@ -0,0 +1,28 @@
# SPDX-License-Identifier: GPL-2.0
CC=gcc
CFLAGS=-std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow
ifeq ("$(DEBUG)","1")
CFLAGS += -g -fsanitize=address -fsanitize=leak -static-libasan
endif
SRCS=$(wildcard *.c)
OBJS=$(patsubst %.c,%.o,${SRCS})
include $(wildcard *.d)
all: ynl.a
ynl.a: $(OBJS)
ar rcs $@ $(OBJS)
clean:
rm -f *.o *.d *~
hardclean: clean
rm -f *.a
%.o: %.c
$(COMPILE.c) -MMD -c -o $@ $<
.PHONY: all clean
.DEFAULT_GOAL=all

901
tools/net/ynl/lib/ynl.c Normal file
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@ -0,0 +1,901 @@
// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
#include <errno.h>
#include <poll.h>
#include <string.h>
#include <stdlib.h>
#include <linux/types.h>
#include <libmnl/libmnl.h>
#include <linux/genetlink.h>
#include "ynl.h"
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(*arr))
#define __yerr_msg(yse, _msg...) \
({ \
struct ynl_error *_yse = (yse); \
\
if (_yse) { \
snprintf(_yse->msg, sizeof(_yse->msg) - 1, _msg); \
_yse->msg[sizeof(_yse->msg) - 1] = 0; \
} \
})
#define __yerr_code(yse, _code...) \
({ \
struct ynl_error *_yse = (yse); \
\
if (_yse) { \
_yse->code = _code; \
} \
})
#define __yerr(yse, _code, _msg...) \
({ \
__yerr_msg(yse, _msg); \
__yerr_code(yse, _code); \
})
#define __perr(yse, _msg) __yerr(yse, errno, _msg)
#define yerr_msg(_ys, _msg...) __yerr_msg(&(_ys)->err, _msg)
#define yerr(_ys, _code, _msg...) __yerr(&(_ys)->err, _code, _msg)
#define perr(_ys, _msg) __yerr(&(_ys)->err, errno, _msg)
/* -- Netlink boiler plate */
static int
ynl_err_walk_report_one(struct ynl_policy_nest *policy, unsigned int type,
char *str, int str_sz, int *n)
{
if (!policy) {
if (*n < str_sz)
*n += snprintf(str, str_sz, "!policy");
return 1;
}
if (type > policy->max_attr) {
if (*n < str_sz)
*n += snprintf(str, str_sz, "!oob");
return 1;
}
if (!policy->table[type].name) {
if (*n < str_sz)
*n += snprintf(str, str_sz, "!name");
return 1;
}
if (*n < str_sz)
*n += snprintf(str, str_sz - *n,
".%s", policy->table[type].name);
return 0;
}
static int
ynl_err_walk(struct ynl_sock *ys, void *start, void *end, unsigned int off,
struct ynl_policy_nest *policy, char *str, int str_sz,
struct ynl_policy_nest **nest_pol)
{
unsigned int astart_off, aend_off;
const struct nlattr *attr;
unsigned int data_len;
unsigned int type;
bool found = false;
int n = 0;
if (!policy) {
if (n < str_sz)
n += snprintf(str, str_sz, "!policy");
return n;
}
data_len = end - start;
mnl_attr_for_each_payload(start, data_len) {
astart_off = (char *)attr - (char *)start;
aend_off = astart_off + mnl_attr_get_payload_len(attr);
if (aend_off <= off)
continue;
found = true;
break;
}
if (!found)
return 0;
off -= astart_off;
type = mnl_attr_get_type(attr);
if (ynl_err_walk_report_one(policy, type, str, str_sz, &n))
return n;
if (!off) {
if (nest_pol)
*nest_pol = policy->table[type].nest;
return n;
}
if (!policy->table[type].nest) {
if (n < str_sz)
n += snprintf(str, str_sz, "!nest");
return n;
}
off -= sizeof(struct nlattr);
start = mnl_attr_get_payload(attr);
end = start + mnl_attr_get_payload_len(attr);
return n + ynl_err_walk(ys, start, end, off, policy->table[type].nest,
&str[n], str_sz - n, nest_pol);
}
#define NLMSGERR_ATTR_MISS_TYPE (NLMSGERR_ATTR_POLICY + 1)
#define NLMSGERR_ATTR_MISS_NEST (NLMSGERR_ATTR_POLICY + 2)
#define NLMSGERR_ATTR_MAX (NLMSGERR_ATTR_MAX + 2)
static int
ynl_ext_ack_check(struct ynl_sock *ys, const struct nlmsghdr *nlh,
unsigned int hlen)
{
const struct nlattr *tb[NLMSGERR_ATTR_MAX + 1] = {};
char miss_attr[sizeof(ys->err.msg)];
char bad_attr[sizeof(ys->err.msg)];
const struct nlattr *attr;
const char *str = NULL;
if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))
return MNL_CB_OK;
mnl_attr_for_each(attr, nlh, hlen) {
unsigned int len, type;
len = mnl_attr_get_payload_len(attr);
type = mnl_attr_get_type(attr);
if (type > NLMSGERR_ATTR_MAX)
continue;
tb[type] = attr;
switch (type) {
case NLMSGERR_ATTR_OFFS:
case NLMSGERR_ATTR_MISS_TYPE:
case NLMSGERR_ATTR_MISS_NEST:
if (len != sizeof(__u32))
return MNL_CB_ERROR;
break;
case NLMSGERR_ATTR_MSG:
str = mnl_attr_get_payload(attr);
if (str[len - 1])
return MNL_CB_ERROR;
break;
default:
break;
}
}
bad_attr[0] = '\0';
miss_attr[0] = '\0';
if (tb[NLMSGERR_ATTR_OFFS]) {
unsigned int n, off;
void *start, *end;
ys->err.attr_offs = mnl_attr_get_u32(tb[NLMSGERR_ATTR_OFFS]);
n = snprintf(bad_attr, sizeof(bad_attr), "%sbad attribute: ",
str ? " (" : "");
start = mnl_nlmsg_get_payload_offset(ys->nlh,
sizeof(struct genlmsghdr));
end = mnl_nlmsg_get_payload_tail(ys->nlh);
off = ys->err.attr_offs;
off -= sizeof(struct nlmsghdr);
off -= sizeof(struct genlmsghdr);
n += ynl_err_walk(ys, start, end, off, ys->req_policy,
&bad_attr[n], sizeof(bad_attr) - n, NULL);
if (n >= sizeof(bad_attr))
n = sizeof(bad_attr) - 1;
bad_attr[n] = '\0';
}
if (tb[NLMSGERR_ATTR_MISS_TYPE]) {
struct ynl_policy_nest *nest_pol = NULL;
unsigned int n, off, type;
void *start, *end;
int n2;
type = mnl_attr_get_u32(tb[NLMSGERR_ATTR_MISS_TYPE]);
n = snprintf(miss_attr, sizeof(miss_attr), "%smissing attribute: ",
bad_attr[0] ? ", " : (str ? " (" : ""));
start = mnl_nlmsg_get_payload_offset(ys->nlh,
sizeof(struct genlmsghdr));
end = mnl_nlmsg_get_payload_tail(ys->nlh);
nest_pol = ys->req_policy;
if (tb[NLMSGERR_ATTR_MISS_NEST]) {
off = mnl_attr_get_u32(tb[NLMSGERR_ATTR_MISS_NEST]);
off -= sizeof(struct nlmsghdr);
off -= sizeof(struct genlmsghdr);
n += ynl_err_walk(ys, start, end, off, ys->req_policy,
&miss_attr[n], sizeof(miss_attr) - n,
&nest_pol);
}
n2 = 0;
ynl_err_walk_report_one(nest_pol, type, &miss_attr[n],
sizeof(miss_attr) - n, &n2);
n += n2;
if (n >= sizeof(miss_attr))
n = sizeof(miss_attr) - 1;
miss_attr[n] = '\0';
}
/* Implicitly depend on ys->err.code already set */
if (str)
yerr_msg(ys, "Kernel %s: '%s'%s%s%s",
ys->err.code ? "error" : "warning",
str, bad_attr, miss_attr,
bad_attr[0] || miss_attr[0] ? ")" : "");
else if (bad_attr[0] || miss_attr[0])
yerr_msg(ys, "Kernel %s: %s%s",
ys->err.code ? "error" : "warning",
bad_attr, miss_attr);
return MNL_CB_OK;
}
static int ynl_cb_error(const struct nlmsghdr *nlh, void *data)
{
const struct nlmsgerr *err = mnl_nlmsg_get_payload(nlh);
struct ynl_parse_arg *yarg = data;
unsigned int hlen;
int code;
code = err->error >= 0 ? err->error : -err->error;
yarg->ys->err.code = code;
errno = code;
hlen = sizeof(*err);
if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
hlen += mnl_nlmsg_get_payload_len(&err->msg);
ynl_ext_ack_check(yarg->ys, nlh, hlen);
return code ? MNL_CB_ERROR : MNL_CB_STOP;
}
static int ynl_cb_done(const struct nlmsghdr *nlh, void *data)
{
struct ynl_parse_arg *yarg = data;
int err;
err = *(int *)NLMSG_DATA(nlh);
if (err < 0) {
yarg->ys->err.code = -err;
errno = -err;
ynl_ext_ack_check(yarg->ys, nlh, sizeof(int));
return MNL_CB_ERROR;
}
return MNL_CB_STOP;
}
static int ynl_cb_noop(const struct nlmsghdr *nlh, void *data)
{
return MNL_CB_OK;
}
mnl_cb_t ynl_cb_array[NLMSG_MIN_TYPE] = {
[NLMSG_NOOP] = ynl_cb_noop,
[NLMSG_ERROR] = ynl_cb_error,
[NLMSG_DONE] = ynl_cb_done,
[NLMSG_OVERRUN] = ynl_cb_noop,
};
/* Attribute validation */
int ynl_attr_validate(struct ynl_parse_arg *yarg, const struct nlattr *attr)
{
struct ynl_policy_attr *policy;
unsigned int type, len;
unsigned char *data;
data = mnl_attr_get_payload(attr);
len = mnl_attr_get_payload_len(attr);
type = mnl_attr_get_type(attr);
if (type > yarg->rsp_policy->max_attr) {
yerr(yarg->ys, YNL_ERROR_INTERNAL,
"Internal error, validating unknown attribute");
return -1;
}
policy = &yarg->rsp_policy->table[type];
switch (policy->type) {
case YNL_PT_REJECT:
yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
"Rejected attribute (%s)", policy->name);
return -1;
case YNL_PT_IGNORE:
break;
case YNL_PT_U8:
if (len == sizeof(__u8))
break;
yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
"Invalid attribute (u8 %s)", policy->name);
return -1;
case YNL_PT_U16:
if (len == sizeof(__u16))
break;
yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
"Invalid attribute (u16 %s)", policy->name);
return -1;
case YNL_PT_U32:
if (len == sizeof(__u32))
break;
yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
"Invalid attribute (u32 %s)", policy->name);
return -1;
case YNL_PT_U64:
if (len == sizeof(__u64))
break;
yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
"Invalid attribute (u64 %s)", policy->name);
return -1;
case YNL_PT_FLAG:
/* Let flags grow into real attrs, why not.. */
break;
case YNL_PT_NEST:
if (!len || len >= sizeof(*attr))
break;
yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
"Invalid attribute (nest %s)", policy->name);
return -1;
case YNL_PT_BINARY:
if (!policy->len || len == policy->len)
break;
yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
"Invalid attribute (binary %s)", policy->name);
return -1;
case YNL_PT_NUL_STR:
if ((!policy->len || len <= policy->len) && !data[len - 1])
break;
yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
"Invalid attribute (string %s)", policy->name);
return -1;
default:
yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
"Invalid attribute (unknown %s)", policy->name);
return -1;
}
return 0;
}
/* Generic code */
static void ynl_err_reset(struct ynl_sock *ys)
{
ys->err.code = 0;
ys->err.attr_offs = 0;
ys->err.msg[0] = 0;
}
struct nlmsghdr *ynl_msg_start(struct ynl_sock *ys, __u32 id, __u16 flags)
{
struct nlmsghdr *nlh;
ynl_err_reset(ys);
nlh = ys->nlh = mnl_nlmsg_put_header(ys->tx_buf);
nlh->nlmsg_type = id;
nlh->nlmsg_flags = flags;
nlh->nlmsg_seq = ++ys->seq;
return nlh;
}
struct nlmsghdr *
ynl_gemsg_start(struct ynl_sock *ys, __u32 id, __u16 flags,
__u8 cmd, __u8 version)
{
struct genlmsghdr gehdr;
struct nlmsghdr *nlh;
void *data;
nlh = ynl_msg_start(ys, id, flags);
memset(&gehdr, 0, sizeof(gehdr));
gehdr.cmd = cmd;
gehdr.version = version;
data = mnl_nlmsg_put_extra_header(nlh, sizeof(gehdr));
memcpy(data, &gehdr, sizeof(gehdr));
return nlh;
}
void ynl_msg_start_req(struct ynl_sock *ys, __u32 id)
{
ynl_msg_start(ys, id, NLM_F_REQUEST | NLM_F_ACK);
}
void ynl_msg_start_dump(struct ynl_sock *ys, __u32 id)
{
ynl_msg_start(ys, id, NLM_F_REQUEST | NLM_F_ACK | NLM_F_DUMP);
}
struct nlmsghdr *
ynl_gemsg_start_req(struct ynl_sock *ys, __u32 id, __u8 cmd, __u8 version)
{
return ynl_gemsg_start(ys, id, NLM_F_REQUEST | NLM_F_ACK, cmd, version);
}
struct nlmsghdr *
ynl_gemsg_start_dump(struct ynl_sock *ys, __u32 id, __u8 cmd, __u8 version)
{
return ynl_gemsg_start(ys, id, NLM_F_REQUEST | NLM_F_ACK | NLM_F_DUMP,
cmd, version);
}
int ynl_recv_ack(struct ynl_sock *ys, int ret)
{
if (!ret) {
yerr(ys, YNL_ERROR_EXPECT_ACK,
"Expecting an ACK but nothing received");
return -1;
}
ret = mnl_socket_recvfrom(ys->sock, ys->rx_buf, MNL_SOCKET_BUFFER_SIZE);
if (ret < 0) {
perr(ys, "Socket receive failed");
return ret;
}
return mnl_cb_run(ys->rx_buf, ret, ys->seq, ys->portid,
ynl_cb_null, ys);
}
int ynl_cb_null(const struct nlmsghdr *nlh, void *data)
{
struct ynl_parse_arg *yarg = data;
yerr(yarg->ys, YNL_ERROR_UNEXPECT_MSG,
"Received a message when none were expected");
return MNL_CB_ERROR;
}
/* Init/fini and genetlink boiler plate */
static int
ynl_get_family_info_mcast(struct ynl_sock *ys, const struct nlattr *mcasts)
{
const struct nlattr *entry, *attr;
unsigned int i;
mnl_attr_for_each_nested(attr, mcasts)
ys->n_mcast_groups++;
if (!ys->n_mcast_groups)
return 0;
ys->mcast_groups = calloc(ys->n_mcast_groups,
sizeof(*ys->mcast_groups));
if (!ys->mcast_groups)
return MNL_CB_ERROR;
i = 0;
mnl_attr_for_each_nested(entry, mcasts) {
mnl_attr_for_each_nested(attr, entry) {
if (mnl_attr_get_type(attr) == CTRL_ATTR_MCAST_GRP_ID)
ys->mcast_groups[i].id = mnl_attr_get_u32(attr);
if (mnl_attr_get_type(attr) == CTRL_ATTR_MCAST_GRP_NAME) {
strncpy(ys->mcast_groups[i].name,
mnl_attr_get_str(attr),
GENL_NAMSIZ - 1);
ys->mcast_groups[i].name[GENL_NAMSIZ - 1] = 0;
}
}
}
return 0;
}
static int ynl_get_family_info_cb(const struct nlmsghdr *nlh, void *data)
{
struct ynl_parse_arg *yarg = data;
struct ynl_sock *ys = yarg->ys;
const struct nlattr *attr;
bool found_id = true;
mnl_attr_for_each(attr, nlh, sizeof(struct genlmsghdr)) {
if (mnl_attr_get_type(attr) == CTRL_ATTR_MCAST_GROUPS)
if (ynl_get_family_info_mcast(ys, attr))
return MNL_CB_ERROR;
if (mnl_attr_get_type(attr) != CTRL_ATTR_FAMILY_ID)
continue;
if (mnl_attr_get_payload_len(attr) != sizeof(__u16)) {
yerr(ys, YNL_ERROR_ATTR_INVALID, "Invalid family ID");
return MNL_CB_ERROR;
}
ys->family_id = mnl_attr_get_u16(attr);
found_id = true;
}
if (!found_id) {
yerr(ys, YNL_ERROR_ATTR_MISSING, "Family ID missing");
return MNL_CB_ERROR;
}
return MNL_CB_OK;
}
static int ynl_sock_read_family(struct ynl_sock *ys, const char *family_name)
{
struct ynl_parse_arg yarg = { .ys = ys, };
struct nlmsghdr *nlh;
int err;
nlh = ynl_gemsg_start_req(ys, GENL_ID_CTRL, CTRL_CMD_GETFAMILY, 1);
mnl_attr_put_strz(nlh, CTRL_ATTR_FAMILY_NAME, family_name);
err = mnl_socket_sendto(ys->sock, nlh, nlh->nlmsg_len);
if (err < 0) {
perr(ys, "failed to request socket family info");
return err;
}
err = mnl_socket_recvfrom(ys->sock, ys->rx_buf, MNL_SOCKET_BUFFER_SIZE);
if (err <= 0) {
perr(ys, "failed to receive the socket family info");
return err;
}
err = mnl_cb_run2(ys->rx_buf, err, ys->seq, ys->portid,
ynl_get_family_info_cb, &yarg,
ynl_cb_array, ARRAY_SIZE(ynl_cb_array));
if (err < 0) {
free(ys->mcast_groups);
perr(ys, "failed to receive the socket family info - no such family?");
return err;
}
return ynl_recv_ack(ys, err);
}
struct ynl_sock *
ynl_sock_create(const struct ynl_family *yf, struct ynl_error *yse)
{
struct ynl_sock *ys;
int one = 1;
ys = malloc(sizeof(*ys) + 2 * MNL_SOCKET_BUFFER_SIZE);
if (!ys)
return NULL;
memset(ys, 0, sizeof(*ys));
ys->family = yf;
ys->tx_buf = &ys->raw_buf[0];
ys->rx_buf = &ys->raw_buf[MNL_SOCKET_BUFFER_SIZE];
ys->ntf_last_next = &ys->ntf_first;
ys->sock = mnl_socket_open(NETLINK_GENERIC);
if (!ys->sock) {
__perr(yse, "failed to create a netlink socket");
goto err_free_sock;
}
if (mnl_socket_setsockopt(ys->sock, NETLINK_CAP_ACK,
&one, sizeof(one))) {
__perr(yse, "failed to enable netlink ACK");
goto err_close_sock;
}
if (mnl_socket_setsockopt(ys->sock, NETLINK_EXT_ACK,
&one, sizeof(one))) {
__perr(yse, "failed to enable netlink ext ACK");
goto err_close_sock;
}
ys->seq = random();
ys->portid = mnl_socket_get_portid(ys->sock);
if (ynl_sock_read_family(ys, yf->name)) {
if (yse)
memcpy(yse, &ys->err, sizeof(*yse));
goto err_close_sock;
}
return ys;
err_close_sock:
mnl_socket_close(ys->sock);
err_free_sock:
free(ys);
return NULL;
}
void ynl_sock_destroy(struct ynl_sock *ys)
{
struct ynl_ntf_base_type *ntf;
mnl_socket_close(ys->sock);
while ((ntf = ynl_ntf_dequeue(ys)))
ynl_ntf_free(ntf);
free(ys->mcast_groups);
free(ys);
}
/* YNL multicast handling */
void ynl_ntf_free(struct ynl_ntf_base_type *ntf)
{
ntf->free(ntf);
}
int ynl_subscribe(struct ynl_sock *ys, const char *grp_name)
{
unsigned int i;
int err;
for (i = 0; i < ys->n_mcast_groups; i++)
if (!strcmp(ys->mcast_groups[i].name, grp_name))
break;
if (i == ys->n_mcast_groups) {
yerr(ys, ENOENT, "Multicast group '%s' not found", grp_name);
return -1;
}
err = mnl_socket_setsockopt(ys->sock, NETLINK_ADD_MEMBERSHIP,
&ys->mcast_groups[i].id,
sizeof(ys->mcast_groups[i].id));
if (err < 0) {
perr(ys, "Subscribing to multicast group failed");
return -1;
}
return 0;
}
int ynl_socket_get_fd(struct ynl_sock *ys)
{
return mnl_socket_get_fd(ys->sock);
}
struct ynl_ntf_base_type *ynl_ntf_dequeue(struct ynl_sock *ys)
{
struct ynl_ntf_base_type *ntf;
if (!ynl_has_ntf(ys))
return NULL;
ntf = ys->ntf_first;
ys->ntf_first = ntf->next;
if (ys->ntf_last_next == &ntf->next)
ys->ntf_last_next = &ys->ntf_first;
return ntf;
}
static int ynl_ntf_parse(struct ynl_sock *ys, const struct nlmsghdr *nlh)
{
struct ynl_parse_arg yarg = { .ys = ys, };
const struct ynl_ntf_info *info;
struct ynl_ntf_base_type *rsp;
struct genlmsghdr *gehdr;
int ret;
gehdr = mnl_nlmsg_get_payload(nlh);
if (gehdr->cmd >= ys->family->ntf_info_size)
return MNL_CB_ERROR;
info = &ys->family->ntf_info[gehdr->cmd];
if (!info->cb)
return MNL_CB_ERROR;
rsp = calloc(1, info->alloc_sz);
rsp->free = info->free;
yarg.data = rsp->data;
yarg.rsp_policy = info->policy;
ret = info->cb(nlh, &yarg);
if (ret <= MNL_CB_STOP)
goto err_free;
rsp->family = nlh->nlmsg_type;
rsp->cmd = gehdr->cmd;
*ys->ntf_last_next = rsp;
ys->ntf_last_next = &rsp->next;
return MNL_CB_OK;
err_free:
info->free(rsp);
return MNL_CB_ERROR;
}
static int ynl_ntf_trampoline(const struct nlmsghdr *nlh, void *data)
{
return ynl_ntf_parse((struct ynl_sock *)data, nlh);
}
int ynl_ntf_check(struct ynl_sock *ys)
{
ssize_t len;
int err;
do {
/* libmnl doesn't let us pass flags to the recv to make
* it non-blocking so we need to poll() or peek() :|
*/
struct pollfd pfd = { };
pfd.fd = mnl_socket_get_fd(ys->sock);
pfd.events = POLLIN;
err = poll(&pfd, 1, 1);
if (err < 1)
return err;
len = mnl_socket_recvfrom(ys->sock, ys->rx_buf,
MNL_SOCKET_BUFFER_SIZE);
if (len < 0)
return len;
err = mnl_cb_run2(ys->rx_buf, len, ys->seq, ys->portid,
ynl_ntf_trampoline, ys,
ynl_cb_array, NLMSG_MIN_TYPE);
if (err < 0)
return err;
} while (err > 0);
return 0;
}
/* YNL specific helpers used by the auto-generated code */
struct ynl_dump_list_type *YNL_LIST_END = (void *)(0xb4d123);
void ynl_error_unknown_notification(struct ynl_sock *ys, __u8 cmd)
{
yerr(ys, YNL_ERROR_UNKNOWN_NTF,
"Unknown notification message type '%d'", cmd);
}
int ynl_error_parse(struct ynl_parse_arg *yarg, const char *msg)
{
yerr(yarg->ys, YNL_ERROR_INV_RESP, "Error parsing response: %s", msg);
return MNL_CB_ERROR;
}
static int
ynl_check_alien(struct ynl_sock *ys, const struct nlmsghdr *nlh, __u32 rsp_cmd)
{
struct genlmsghdr *gehdr;
if (mnl_nlmsg_get_payload_len(nlh) < sizeof(*gehdr)) {
yerr(ys, YNL_ERROR_INV_RESP,
"Kernel responded with truncated message");
return -1;
}
gehdr = mnl_nlmsg_get_payload(nlh);
if (gehdr->cmd != rsp_cmd)
return ynl_ntf_parse(ys, nlh);
return 0;
}
static int ynl_req_trampoline(const struct nlmsghdr *nlh, void *data)
{
struct ynl_req_state *yrs = data;
int ret;
ret = ynl_check_alien(yrs->yarg.ys, nlh, yrs->rsp_cmd);
if (ret)
return ret < 0 ? MNL_CB_ERROR : MNL_CB_OK;
return yrs->cb(nlh, &yrs->yarg);
}
int ynl_exec(struct ynl_sock *ys, struct nlmsghdr *req_nlh,
struct ynl_req_state *yrs)
{
ssize_t len;
int err;
err = mnl_socket_sendto(ys->sock, req_nlh, req_nlh->nlmsg_len);
if (err < 0)
return err;
do {
len = mnl_socket_recvfrom(ys->sock, ys->rx_buf,
MNL_SOCKET_BUFFER_SIZE);
if (len < 0)
return len;
err = mnl_cb_run2(ys->rx_buf, len, ys->seq, ys->portid,
ynl_req_trampoline, yrs,
ynl_cb_array, NLMSG_MIN_TYPE);
if (err < 0)
return err;
} while (err > 0);
return 0;
}
static int ynl_dump_trampoline(const struct nlmsghdr *nlh, void *data)
{
struct ynl_dump_state *ds = data;
struct ynl_dump_list_type *obj;
struct ynl_parse_arg yarg = {};
int ret;
ret = ynl_check_alien(ds->ys, nlh, ds->rsp_cmd);
if (ret)
return ret < 0 ? MNL_CB_ERROR : MNL_CB_OK;
obj = calloc(1, ds->alloc_sz);
if (!obj)
return MNL_CB_ERROR;
if (!ds->first)
ds->first = obj;
if (ds->last)
ds->last->next = obj;
ds->last = obj;
yarg.ys = ds->ys;
yarg.rsp_policy = ds->rsp_policy;
yarg.data = &obj->data;
return ds->cb(nlh, &yarg);
}
static void *ynl_dump_end(struct ynl_dump_state *ds)
{
if (!ds->first)
return YNL_LIST_END;
ds->last->next = YNL_LIST_END;
return ds->first;
}
int ynl_exec_dump(struct ynl_sock *ys, struct nlmsghdr *req_nlh,
struct ynl_dump_state *yds)
{
ssize_t len;
int err;
err = mnl_socket_sendto(ys->sock, req_nlh, req_nlh->nlmsg_len);
if (err < 0)
return err;
do {
len = mnl_socket_recvfrom(ys->sock, ys->rx_buf,
MNL_SOCKET_BUFFER_SIZE);
if (len < 0)
goto err_close_list;
err = mnl_cb_run2(ys->rx_buf, len, ys->seq, ys->portid,
ynl_dump_trampoline, yds,
ynl_cb_array, NLMSG_MIN_TYPE);
if (err < 0)
goto err_close_list;
} while (err > 0);
yds->first = ynl_dump_end(yds);
return 0;
err_close_list:
yds->first = ynl_dump_end(yds);
return -1;
}

237
tools/net/ynl/lib/ynl.h Normal file
View File

@ -0,0 +1,237 @@
// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
#ifndef __YNL_C_H
#define __YNL_C_H 1
#include <stddef.h>
#include <libmnl/libmnl.h>
#include <linux/genetlink.h>
#include <linux/types.h>
struct mnl_socket;
struct nlmsghdr;
/*
* User facing code
*/
struct ynl_ntf_base_type;
struct ynl_ntf_info;
struct ynl_sock;
enum ynl_error_code {
YNL_ERROR_NONE = 0,
__YNL_ERRNO_END = 4096,
YNL_ERROR_INTERNAL,
YNL_ERROR_EXPECT_ACK,
YNL_ERROR_EXPECT_MSG,
YNL_ERROR_UNEXPECT_MSG,
YNL_ERROR_ATTR_MISSING,
YNL_ERROR_ATTR_INVALID,
YNL_ERROR_UNKNOWN_NTF,
YNL_ERROR_INV_RESP,
};
/**
* struct ynl_error - error encountered by YNL
* @code: errno (low values) or YNL error code (enum ynl_error_code)
* @attr_offs: offset of bad attribute (for very advanced users)
* @msg: error message
*
* Error information for when YNL operations fail.
* Users should interact with the err member of struct ynl_sock directly.
* The main exception to that rule is ynl_sock_create().
*/
struct ynl_error {
enum ynl_error_code code;
unsigned int attr_offs;
char msg[512];
};
/**
* struct ynl_family - YNL family info
* Family description generated by codegen. Pass to ynl_sock_create().
*/
struct ynl_family {
/* private: */
const char *name;
const struct ynl_ntf_info *ntf_info;
unsigned int ntf_info_size;
};
/**
* struct ynl_sock - YNL wrapped netlink socket
* @err: YNL error descriptor, cleared on every request.
*/
struct ynl_sock {
struct ynl_error err;
/* private: */
const struct ynl_family *family;
struct mnl_socket *sock;
__u32 seq;
__u32 portid;
__u16 family_id;
unsigned int n_mcast_groups;
struct {
unsigned int id;
char name[GENL_NAMSIZ];
} *mcast_groups;
struct ynl_ntf_base_type *ntf_first;
struct ynl_ntf_base_type **ntf_last_next;
struct nlmsghdr *nlh;
struct ynl_policy_nest *req_policy;
unsigned char *tx_buf;
unsigned char *rx_buf;
unsigned char raw_buf[];
};
struct ynl_sock *
ynl_sock_create(const struct ynl_family *yf, struct ynl_error *e);
void ynl_sock_destroy(struct ynl_sock *ys);
#define ynl_dump_foreach(dump, iter) \
for (typeof(dump->obj) *iter = &dump->obj; \
!ynl_dump_obj_is_last(iter); \
iter = ynl_dump_obj_next(iter))
int ynl_subscribe(struct ynl_sock *ys, const char *grp_name);
int ynl_socket_get_fd(struct ynl_sock *ys);
int ynl_ntf_check(struct ynl_sock *ys);
/**
* ynl_has_ntf() - check if socket has *parsed* notifications
* @ys: active YNL socket
*
* Note that this does not take into account notifications sitting
* in netlink socket, just the notifications which have already been
* read and parsed (e.g. during a ynl_ntf_check() call).
*/
static inline bool ynl_has_ntf(struct ynl_sock *ys)
{
return ys->ntf_last_next != &ys->ntf_first;
}
struct ynl_ntf_base_type *ynl_ntf_dequeue(struct ynl_sock *ys);
void ynl_ntf_free(struct ynl_ntf_base_type *ntf);
/*
* YNL internals / low level stuff
*/
/* Generic mnl helper code */
enum ynl_policy_type {
YNL_PT_REJECT = 1,
YNL_PT_IGNORE,
YNL_PT_NEST,
YNL_PT_FLAG,
YNL_PT_BINARY,
YNL_PT_U8,
YNL_PT_U16,
YNL_PT_U32,
YNL_PT_U64,
YNL_PT_NUL_STR,
};
struct ynl_policy_attr {
enum ynl_policy_type type;
unsigned int len;
const char *name;
struct ynl_policy_nest *nest;
};
struct ynl_policy_nest {
unsigned int max_attr;
struct ynl_policy_attr *table;
};
struct ynl_parse_arg {
struct ynl_sock *ys;
struct ynl_policy_nest *rsp_policy;
void *data;
};
struct ynl_dump_list_type {
struct ynl_dump_list_type *next;
unsigned char data[] __attribute__ ((aligned (8)));
};
extern struct ynl_dump_list_type *YNL_LIST_END;
static inline bool ynl_dump_obj_is_last(void *obj)
{
unsigned long uptr = (unsigned long)obj;
uptr -= offsetof(struct ynl_dump_list_type, data);
return uptr == (unsigned long)YNL_LIST_END;
}
static inline void *ynl_dump_obj_next(void *obj)
{
unsigned long uptr = (unsigned long)obj;
struct ynl_dump_list_type *list;
uptr -= offsetof(struct ynl_dump_list_type, data);
list = (void *)uptr;
uptr = (unsigned long)list->next;
uptr += offsetof(struct ynl_dump_list_type, data);
return (void *)uptr;
}
struct ynl_ntf_base_type {
__u16 family;
__u8 cmd;
struct ynl_ntf_base_type *next;
void (*free)(struct ynl_ntf_base_type *ntf);
unsigned char data[] __attribute__ ((aligned (8)));
};
extern mnl_cb_t ynl_cb_array[NLMSG_MIN_TYPE];
struct nlmsghdr *
ynl_gemsg_start_req(struct ynl_sock *ys, __u32 id, __u8 cmd, __u8 version);
struct nlmsghdr *
ynl_gemsg_start_dump(struct ynl_sock *ys, __u32 id, __u8 cmd, __u8 version);
int ynl_attr_validate(struct ynl_parse_arg *yarg, const struct nlattr *attr);
int ynl_recv_ack(struct ynl_sock *ys, int ret);
int ynl_cb_null(const struct nlmsghdr *nlh, void *data);
/* YNL specific helpers used by the auto-generated code */
struct ynl_req_state {
struct ynl_parse_arg yarg;
mnl_cb_t cb;
__u32 rsp_cmd;
};
struct ynl_dump_state {
struct ynl_sock *ys;
struct ynl_policy_nest *rsp_policy;
void *first;
struct ynl_dump_list_type *last;
size_t alloc_sz;
mnl_cb_t cb;
__u32 rsp_cmd;
};
struct ynl_ntf_info {
struct ynl_policy_nest *policy;
mnl_cb_t cb;
size_t alloc_sz;
void (*free)(struct ynl_ntf_base_type *ntf);
};
int ynl_exec(struct ynl_sock *ys, struct nlmsghdr *req_nlh,
struct ynl_req_state *yrs);
int ynl_exec_dump(struct ynl_sock *ys, struct nlmsghdr *req_nlh,
struct ynl_dump_state *yds);
void ynl_error_unknown_notification(struct ynl_sock *ys, __u8 cmd);
int ynl_error_parse(struct ynl_parse_arg *yarg, const char *msg);
#endif

2
tools/net/ynl/ynl-regen.sh
View File

@ -14,7 +14,7 @@ done
KDIR=$(dirname $(dirname $(dirname $(dirname $(realpath $0)))))
files=$(git grep --files-with-matches '^/\* YNL-GEN \(kernel\|uapi\)')
files=$(git grep --files-with-matches '^/\* YNL-GEN \(kernel\|uapi\|user\)')
for f in $files; do
# params: 0 1 2 3
# $YAML YNL-GEN kernel $mode